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All IPCC definitions taken from Climate Change 2007: The Physical Science Basis. Working Group I Contribution to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change, Annex I, Glossary, pp. 941-954. Cambridge University Press.

Is Greenland gaining or losing ice?

What the science says...

Greenland on the whole is losing ice, as confirmed by multiple satellite and on the ground field measurements.

Climate Myth...

Greenland is gaining ice
“[E]ven if it were true that Greenland’s ice had been melting at ‘new record’ rates, after seven and a half years of global cooling global warming cannot be the cause. The true position in Greenland is to be found in Johannessen et al. (2005), where satellite altimetry established that the mean thickness of the entire Greenland ice sheet had increased at 2 inches per year – a total of almost 2 feet – in the 11 years 1993-2003.” (Christopher Monckton)

Confusion caused by anecdotes of structures being buried by accumulating snow on Greenland's ice sheet leads some skeptics to believe Greenland is Gaining Ice. As always, the best way to tease out the truth here by following the research of scientists investigating Greenland's ice mass balance.

In general, the best available science tells us that Greenland is losing ice extensively (Figure 1) and that these losses have drastically increased since the year 2000.

The evidence suggested by a multitude of different measurement techniques suggests that not only is Greenland losing ice but that these ice losses are accelerating at a rapid pace (Velicogna 2009). Further evidence suggests that although ice losses have up to this point primarily occurred in the South and Southwest portions of Greenland, these losses are now spreading to the Northwest sector of the ice sheet (Khan et al 2010).

Although there have been some gains at high altitudes, significant ice losses are occurring at low altitudes (Wouters 2008) along the coastline where glaciers are calving ice into the oceans far quicker than ice is being accumulated at the top of the ice sheet (Rignot and Kanagaratnam 2006).

In conclusion Greenland is losing ice extensively along its margins where fast flowing ice streams are pushing more ice into the ocean than is gained in the center of the ice sheet. For more information on how ice sheets lose mass, a more comprehensive discussion is available here.

Further reading

NASA have a fascinating article Greenland's Ice Island Alarm which looks at the difficulties of measuring ice loss in Greenland and how different techniques using different date (eg - satellites measuring gravity or surface height changes) all agree that Greenland is losing between 150 to 180 gigatonnes of ice per year.

The following animation shows ice mass loss from Greenland as measured by the GRACE gravity satellites:

Comments

There is no argument of overall ice loss in Greenland. The glacial growth is not keeping up with glacial loss.
The argument is the cause. Without the additional heat loss from the earth (vulcanism) through both tectonics and volcanism it might not be a net loss. In other words the reason behind Greenland's and the Arctics ice melt is in question. See the volcano thread.

Science 4 July 2008: Vol. 321. no. 5885, pp. 111 - 113 DOI: 10.1126/science.1158540
Reports
Large and Rapid Melt-Induced Velocity Changes in the Ablation Zone of the Greenland Ice Sheet
R. S. W. van de Wal,* W. Boot, M. R. van den Broeke, C. J. P. P. Smeets, C. H. Reijmer, J. J. A. Donker, J. Oerlemans
Continuous Global Positioning System observations reveal rapid and large ice velocity fluctuations in the western ablation zone of the Greenland Ice Sheet. Within days, ice velocity reacts to increased meltwater production and increases by a factor of 4. Such a response is much stronger and much faster than previously reported. Over a longer period of 17 years, annual ice velocities have decreased slightly, which suggests that the englacial hydraulic system adjusts constantly to the variable meltwater input, which results in a more or less constant ice flux over the years. The positive-feedback mechanism between melt rate and ice velocity appears to be a seasonal process that may have only a limited effect on the response of the ice sheet to climate warming over the next decades.
Institute for Marine and Atmospheric research Utrecht, Utrecht University, Netherlands.

From Peru,
in fig. 3 they show mass change for the period 2003-2008; fig. 2A shows the cumulative mass loss from 1960. The former is a rate of mass loss, the latter just a mass.

r^2 is the so called coefficient of determination. In the case of a simple linear fit it's equal to the square of the correlation coefficient. You may (crudely) interpret it as the fraction of the variation explained by the model curve.

New research on the GRACE results argues there's exaggeration of the ice loss in Greenland and Antarctica data. The current estimates are supposed to ignore isostatic rebound caused by the weight reduction pressing down on the bedrock through the lost ice mass. E.g. this new report claims that the true loss in Greenland is only half of the previously reported 230 Gt per year.

This spectacular reduction is, ofcourse, trumpeted around in the media and denial blogs as exiting news, but 104 Gt per year brings it right into the IPCC 2007 ballpark of 100+ Gt per year. It is, however, much lower then the latest GRACE numbers as published by Velicogna et al. 2009 and 2007, but in the same ballpark as GRACE numbers from Luthcke et al. 2007.

Remote sensing data, surface observations and models indicate new records in 2010 for surface melt and albedo, runoff, the number of days when bare ice is exposed and surface mass balance of the Greenland ice sheet. This was especially true over over its west and southwest regions.

Anyone not see the trend?

In simple words, each bar tells us by how many standard deviations melting in a particular year was above the average. For example, a value of ~ 2 for 2010 means that melting was above the average by two times the ‘variability’ of the melting signal along the period of observation.

Here's a story from the human perspective--Inuit Greenlanders and their changing culture due to changes in ice. It was published in Business Week of all things. Of course, it does hit on the drill, baby, drill aspect of Arctic change.

We need accurate data from any source materials for a valid result. But there is a re-draw map controversy. Times Atlas is at the middle of a debate after publishing a map that revealed a 15 percent decrease in ice mass. Greenland ice mass maps causing political uproar . Greenland is losing some ice mass due to melting. Environmental change due to global warming brings big changes.

The Times atlas controversy appears quite ridiculous. They initially very publicly claimed Greenland had lost 15% of its area, then had to start backpedalling as the complaints from the cryospheric community came rolling in (see RealClimate for a summary). mainly because the Times Atlas in their various statements kept claiming initially that their maps were accurate, then that it was not their fault, it was the fault of the NSIDC, then in their latest concession claim it highlights uncertainty in climate science! Yet all it does is highlight their own incompetence, in taking a >500m thickness map and thinking that this showed ice extent.

From HarperCollins' last statement: "The one thing that is very apparent is that there is no clarity in the scientific and cartographic community on this issue ... ". Dead wrong. There is plenty of clarity on the issue in the science community, it's just that the Times Atlas cartographers got it totally wrong and can't admit it.

In the age of Google Earth and freely-available MODIS imagery, as well as with a media engine keen to highlight "uncertainties" in climate science, such an error, which clouds public understanding of Greenland's actual melt, verges on the unforgivable.

Response:

[DB] "the Times Atlas cartographers got it totally wrong and can't admit it."

As one who spent many years as a professional cartographer, this statement (and your closing paragraph) are spot-on.

I wonder if a Walker type cell could develop between the ever warming Arctic Ocean and the Greenland Ice sheet. Rising warm air contacts the ice, cools and flows down the ice sheet warming by compression and giving its heat to the ice. Warm foen winds cause extreme melting when in contact with ice.